Weibull analysis of modulus of rupture of the slip-cast amorphous silica (SCAS) determined by the 4-point bending test

Modulus of Rupture (MOR) measurements were conducted at room temperature on slip cast amorphous silica bar (50 mm xD7; 8 mm xD7; 6 mm) specimens. The resultant MOR values were then statistically analysed employing the Weibull statistical procedure. It was found that a scatter always exists in the measured MOR values due to the inherent statistical nature of flow distribution in the case of monolithic ceramic specimens. The variability of measured MOR values was modelled using the well-known Weibull statistics. A population (n) of 68 bars was used for Weibull analysis and a Weibull modulus of m = 5.4 was obtained for the total set of all the specimens. The test specimens were generated by slicing from a single slip cast and sintered amorphous silica block (50 mm xD7; 50 mm xD7; 160 mm). An improved Weibull modulus value could be achieved by adopting this procedure as compared to the authors' earlier studies where the test specimens of the size 50 mm xD7; 8 mm xD7; 6 mm were individually processed (slip cast and sintered) and then subjected to MOR test

Methylation status of p14ARF and p16INK4a as detected in pancreatic secretions

The clinical management of pancreatic disease is often hampered by a lack of tissue diagnosis. Endoscopic pancreatography offers the opportunity to investigate exfoliated cells. However, the significance of mere cytological investigation is compromised by an insufficient sensitivity. The evaluation of the molecular background of carcinogenesis hopefully is capable of providing more sensitive diagnostic markers. The p16INK4a-/retinoblastoma tumour-suppressive pathway has been shown to be involved in the development of near to all pancreatic neoplasms. p14ARF is another tumour suppressor located in the immediate neighbourhood of p16INK4a. Promoter methylation has been demonstrated to be a major inactivating mechanism of both genes. We sought to further evaluate the role of the gene locus INK4a methylation status in the endoscopic differentiation of chronic inflammatory and neoplastic pancreatic disease. Pancreatic fluid specimens of 61 patients with either pancreatic carcinoma (PCA: 39), chronic pancreatitis (CP: 16) or a normal pancreatogram (NAD: 6) were retrieved. In order to detect methylation of either the p14ARF or the p16INK4a promoter a methylation-specific PCR protocol was applied. While 19 out of 39 patients with PCA showed p16 promoter methylation (49%), none of the 16 patients with CP revealed p16 promoter methylation. p14ARF methylation was found in a lower percentage of PCA specimens and in none of the samples of patients with CP. These results suggest a specific significance of INK4a for the development of malignant pancreatic disease. Our data further indicate a potential role for INK4a methylation as a diagnostic marker in the endoscopic differentiation of benign and malignant pancreatic disease