Preformed pits as initiation sites for stress corrosion of austenitic stainless steels

A study has been made of the effect of preformed pits on the corrosion behaviour of a heat-treated AISI304 austenitic stainless steel under constant load equal to 80% sp(0.2), at polarization potentials in the imperfect passivity region and under open circuit conditions, exposed to aqueous solutions with diverse SO4/Cl ratios.With polarization in the passive range and a ratio of 1/0.2, as in the first stage of stress corrosion, intergranular attack on the bottom of pits with critical dimensions has been observed. On the walls of the cracks there are characteristic signs of transgranular attack. An increase in temperature causes an increase in the rate of the phenomenon, without leading to the appearance of different forms of corrosion. With polarization in the active range the trend of the crack is always transgranular. Sometimes the crack walls appear to be marked with fine parallel pleats, parallel grooves and micropits. In some conditions - low temperature and very small pits - the formation of martensite, attacked in a highly selective manner, prevents stress corrosion

Diffusion Processes of Aluminium Coatings for the Protection of Austenitic Stainless Steels

An aluminium-coated austenitic stainless steel has been subjected to heat treatments of various durations. The process has led to the formation of inter diffusion zones with characteristic non-directional and columnar structures.The formation of in termetallic compounds such as NiAl or Ni3Al prevails in the non-directional type, while substitutional solid solutions occur in the "columnar " type.One or both these structures can be obtained by balancing and regulating process activity through adequate heat treatments.The development of one or both structures can heighten the characteristics of the coating as regards coating protection or oxidation resistance at high temperatures

Clinical significance of altered nm23-H1, EGFR, RB and p53 expression in bilharzial bladder cancer

<p>Abstract</p> <p>Background</p> <p>Clinical characterization of bladder carcinomas is still inadequate using the standard clinico-pathological prognostic markers. We assessed the correlation between <it>nm23-H1</it>, <it>Rb, EGFR </it>and <it>p53 </it>in relation to the clinical outcome of patients with muscle invasive bilharzial bladder cancer (MI-BBC).</p> <p>Methods</p> <p><it>nm23-H1</it>, <it>Rb, EGFR and p53 </it>expression was assessed in 59 MI-BBC patients using immunohistochemistry and reverse transcription (RT-PCR) and was correlated to the standard clinico-pathological prognostic factors, patient's outcome and the overall survival (OS) rate.</p> <p>Results</p> <p>Overexpression of <it>EGFR </it>and <it>p53 </it>proteins was detected in 66.1% and 35.6%; respectively. Loss of <it>nm23-H1</it>and <it>Rb </it>proteins was detected in 42.4% and 57.6%; respectively. Increased <it>EGFR and </it>loss of <it>nm23-H1 </it>RNA were detected in 61.5% and 36.5%; respectively. There was a statistically significant correlation between <it>p53 </it>and <it>EGFR </it>overexpression (<it>p </it>< 0.0001), <it>nm23 </it>loss (protein and RNA), lymph node status (<it>p </it>< 0.0001); between the incidence of local recurrence and <it>EGFR </it>RNA overexpression (p= 0.003) as well as between the incidence of metastasis and altered <it>Rb </it>expression (<it>p </it>= 0.026), <it>p53 </it>overexpression (<it>p </it>< 0.0001) and mutation (<it>p </it>= 0.04). Advanced disease stage correlated significantly with increased <it>EGFR </it>(protein and RNA) (<it>p </it>= 0.003 & 0.01), reduced <it>nm23-H1 </it>RNA (<it>p </it>= 0.02), altered <it>Rb </it>(<it>p </it>= 0.023), and <it>p53 </it>overexpression (<it>p </it>= 0.004). OS rates correlated significantly, in univariate analysis, with <it>p53 </it>overexpression (<it>p </it>= 0.011), increased <it>EGFR </it>(protein and RNA, <it>p </it>= 0.034&0.031), <it>nm23-H1 RNA </it>loss (<it>p </it>= 0.021) and aberrations of ≥ 2 genes. However, multivariate analysis showed that only high <it>EGFR </it>overexpression, metastatic recurrence, high tumor grade and the combination of ≥ 2 affected markers were independent prognostic factors.</p> <p>Conclusion</p> <p><it>nm23-H1, EGFR </it>and <it>p53 </it>could be used as prognostic biomarkers in MI-BBC patients. In addition to the standard pathological prognostic factors, a combination of these markers (≥ 2) has synergistic effects in stratifying patients into variable risk groups. The higher is the number of altered biomarkers, the higher will be the risk of disease progression and death.</p

Source Tracking Studies in the New York City Watershed

In 1990, the New York City Department of Environmental Protection (DEP) began investigating a seasonal increase in the fecal coliform concentrations in Kensico Reservoir, Valhalla, New York. This location is significant since Kensico Reservoir is the last storage reservoir prior to chlorination for approximately 80-90% of the drinking water that is delivered to nine million New York City residents daily. This study, coupled with the new coliform regulations mandated by the Surface Water Treatment Rule (SWTR), required a new approach for the way DEP microbiologists would respond to all future investigations. The DEP formed a Research Microbiology Unit that would work with the routine microbiology staff to provide more in-depth investigations into unusual occurrences in the upstate watershed. The main function of this group has been to determine if fecal contamination, as suggested by microbial indicator analyses, is coming from human or non-human sources. This approach has helped to narrow down sources of fecal input in the watershed, and allowed preventative measures to be taken to greatly reduce or eliminate further contamination. In addition, the specificity of some of this work has also helped to assess the human infective potential of samples in some situations. This has been of great value when determining potential health risks to consumers. The routine microbial indicators used by the Department have been total coliform, fecal coliform, Escherichia coli, Giardia spp. and Cryptosporidium spp. Follow up analysis used to narrow down sources of fecal contamination have included: fecal streptococci, enterococci, FC:FS ratios, serotyping, electrophoretic typing, F-specific RNA coliphage typing, Ribotyping (RT), Small Sub-Unit (SSU) rRNA based Polymerase Chain Reaction (PCR), Restriction Fragment Length Polymorphism (RFLP) and gene sequencing. The level of confidence associated with each of these techniques is unique to each investigation and has also been dependant upon other water quality data and supplemental information provided. In studies where multiple techniques have been applied, and have been in agreement, the confidence in the conclusion has been greatly increased. Some of these techniques have not performed as well as others, and some have only appeared to be of benefit when used in combination with other techniques. Each investigation has been somewhat distinctive and has required a certain method, or combination of techniques, to reach a result. Conversely, there have been times when applied methods have not been helpful in making a source determination and no conclusions could be made. Consequently, the DEP continues to investigate and develop methods to become part of its “microbial toolbox”, and there are continued plans for future work in the science of source tracking

Formazione di fasi alluminio-nichel su acciaio abasso carbonio

[No abstract available