Magnetic properties of nano-crystalline Fe-Cr alloys prepared bymechanical alloying

Fe-Cr powdered alloys synthesized via mechanical attrition have been examined by magnetization and 57Fe Mossbauer spectroscopy. Mossbauer studies reveal that Fe1-xCrx becomes paramagnetic for x⩾0.46 after 100 h milling. Magnetization results suggest that a significant reduction of Fe magnetic moment occurs in the nano-crystalline Fe1-xCrx alloys. Curie temperature for x=0.46 and 0.69 lies below liquid N 2 and liquid He temperature, respectively

p53 expression in squamous dysplasia associated with carcinoma of the oesophagus: evidence for field carcinogenesis

Squamous epithelial dysplasia is often observed multifocally in the cancerous oesophagus and is presumably considered to be a pre-cancerous lesion. A mutation of the p53 tumour suppressor gene is commonly identified in oesophageal cancer and dysplasia. p53 mutations can be anticipated immunohistochemically. In order to confirm the biological and clinical significance of p53 expressions in oesophageal field carcinogenesis, immunostaining for p53 in cancerous and multifocal precancerous lesions from resected human oesophagus was systematically investigated, while paying special attention to the contiguity of these lesions. Lesions expressing p53 were detected in 46.5% (20 of 43 lesions) of the invasive carcinoma, and in 51.0% (46 of 90 lesions) of the carcinoma in situ, and in 51.4% (92 of 179 lesions) of the dysplasia. Next, the p53 expression in dysplasia was compared with that in carcinoma for the same case. 37 of 39 (94.8%) dysplasias contiguous to p53-positive carcinomas also expressed p53 (P < 0.0001). On the other hand, the isolated dysplasias without contiguity to p53-positive carcinomas, only expressed p53 protein in 44.0% (11 of 25 lesions). No significant correlations were found between the p53 staining and either the clinicopathological features or prognosis. Discordant p53 alterations, such as those seen in cancerous and isolated precancerous lesions, may thus demonstrate further evidence for a multicentric or field carcinogenesis of the human oesophagus. © 2000 Cancer Research Campaig

Exploring the micro-to-macro response of granular soils with real particle shapes via \u1d741\u1d46a\u1d47b-aided DEM analyses

This contribution provides high fidelity images of real granular materials with the aid of X-ray micro computed tomography (μCT ), and employs a multi-sphere approximation to reconstruct non-spherical particles. Through the discrete element method (DEM) simulations on granular samples composed of these non-spherical clumps, the effect of particle shape on the macroscopic mechanical response and microscopic soil fabric evolution is examined for sheared soil assemblies under triaxial loading conditions. Simulation results indicate that materials with more irregular particles tend to show higher shear resistance in both peak and critical stresses, while more sphere-like materials tend to exhibit lower void ratio and mean coordination number values under isotropic loading conditions and in the critical state. The proposed critical state parameters for describing the sensitivity of the mean coordination number to confining pressures are larger as particles become more irregular. At a microscopic level of observation, more irregular materials appear to exhibit higher fabric anisotropy in terms of contact normal and particle orientation in the critical state. The critical stress ratio determined through experimental and simulation results are found to be linearly linked to the shape-weighted fabric anisotropy index