The Effect of Mn Depleted Surface Layer on the Corrosion Resistance of Shape Memory Fe-Mn-Si-Cr Alloys

In this work, we have examined Fe-Mn-Si-Cr alloys possessing a good shape memory effect due to a high Mn content (28 wt pct). The addition of Cr (5 wt pct) was made in order to give fairly good corrosion resistance to the alloy. But we have verified that even in moderately corrosive environ-ments, the presence of chromium does not bear any passivation. On the other hand, we have found that the alloy can acquire corrosion resistance by means of the formation of a Mn-depleted surface layer obtained by heating the alloy at high temperature (.10507C) in air. This modified layer forms since manganese is selectively oxidized with respect to the other components. The adhesion of this layer is maintained even under severe stress if the thickness of the modified region does not exceed 20mm. Under this limit, the shape memory characteristics of the alloy are not affected, and at the same time, the specimen acquires properties of passivity comparable with one of the most common austenitic stainless steels at the presence of the same environmental conditions

Prevalence of nonpolypoid colorectal neoplasia: an italian multicenter observational study

BACKGROUND AND STUDY AIM: The aim of this study was to assess the prevalence of nonpolypoid lesions (NPLs) in Italy and their risk of containing neoplasia or advanced histology.PATIENTS AND METHODS: This was a multicenter cross-sectional observational study on consecutive patients undergoing total colonoscopy over a 3-month period in 80 Italian centers.RESULTS: In all, 27,400 total colonoscopies were analyzed. Cancer was diagnosed in 801 patients (2.9 %). A total of 6553 precancerous lesions were detected in 5609 patients. Of these, 4154 patients (74.1 %) had polypoid lesions and 1455 patients (25.9 %) had NPLs. Therefore, the prevalence of NPLs was 5.3 % (95 %CI 5.0 - 5.6). NPLs larger than 10 mm were detected in 254 patients (17.5 %). NPLs were more predominant in the proximal colon (OR 2.92, 95 %CI 2.56 - 3.43; P < 0.0001 vs. polypoid lesions). Neoplastic tissue was diagnosed in 79.0 % and advanced histology (high-grade intraepithelial neoplasia or more) in 20.9 % of resected lesions. The risk of advanced histology was similar for polypoid and nonpolypoid lesions when adjusted for size. Depressed lesions had the highest risk of advanced histology (OR 10.56, 95 %CI 6.02 - 18.55; P < 0.0000 vs. flat-elevated). Age was an independent predictor of both neoplasia and advanced histology ( P = 0.0001).CONCLUSIONS: NPLs are relatively common in the Italian population, with a prevalence similar to that in other Western series. NPLs are not more aggressive than polypoid lesions, except for those with depressed morphology