Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed

Indentation fracture toughness and surface flaw analysis of sintered alumina/SiC nanocomposites

The fracture toughness (K1c) of pressureless-sintered monolithic α-alumina and its composites with 5, 10 and 15 vol% SiC nano-sized particles was investigated using Vickers indentation and a new Hertzian (ball) indentation technique. Both methods showed that the fracture toughness of the composites is better than that of alumina, although the results from the Vickers indentations were complicated by a change in crack geometry from median/radial (alumina) to Palmqvist (composites) An analysis of the number and size of surface flaws using the Hertzian test indicates that, for the same polishing treatment, the composites have a better surface finish. © 1996 Elsevier Science Limited

Pressureless sintering and elastic constants of Al2O3-SiC 'nanocomposites'

A study is presented of how to obtain very near theoretical densities (≥99-6%) in Al2O3-SiC 'nanocomposites' by pressureless sintering. Several factors are considered in order to achieve the optimal densification. The most important factors are: good dispersion of SiC particles in the matrix, cold-isostatic pressing of green samples and use of a relatively coarse-sized bedding powder (which allows efficient effusion of carbon monoxide from the sample), correct choice of sintering temperature (which depends on the size of alumina particles), and the use of a nitrogen atmosphere during sintering. The elastic constants of the nanocomposites produced depend on the degree of densification. About 2% reduction from theoretical density leads to about a 6% reduction of the Young's modulus. The experimentally obtained moduli are correlated with three models that relate porosity to Young's modulus. © 1997 Elsevier Science Limited. All rights reserved