Expression of p53, p21^(CIP1/WAF1) and eIF4E in the adjacent tissues of oral squamous cell carcinoma:establishing the molecular boundary and a cancer progression model

The present study evaluated the expression of key molecules and the status of DNA in both oral squamous cell carcinoma（OSCC） and adjacent tissues to establish a molecular surgical boundary and provide a cancer progression model. Biopsy samples from 50 OSCC patients were divided into T（cancer）, P1（0–0.5 cm）, P2（0.5–1 cm）, P3（1–1.5 cm） and P4（1.5–2 cm） groups based on the distances from the visible boundary of the primary focus. Twenty samples of normal mucosa were used as controls. We used immunohistochemical staining and flow cytometry to evaluate p53, p21CIP1/WAF1, e IF4 E and Ki-67 expression and to determine DNA status, respectively. Sub-mucosal invasion was present in the P1 and P2 groups as determined by haematoxylin and eosin staining.Mutant p53 expression decreased gradually from cancerous to normal mucosae, whereas p21CIP1/WAF1 expression displayed an opposite trend. e IF4 E expression decreased from cancerous to normal mucosae. Ki-67 expression, the heteroploidy ratio, S-phase fraction and proliferative index decreased gradually with the distance from the tumour centre. Based on these results, we suggest that the resection boundary in OSCC surgery should be beyond 2 cm from the tumour. Additionally, the adjacent tissues of the primary focus could be used as a model for assessing cancer progression.

MECHANISM OF BOUNDARY LUBRICATION UNDER POINT CONTACT

The acid number of the mixed solution of 150SN oil and oleic acid characterizes the volume content of oleic acid in the solution, based on which the adsorptive capability of oleic acid is studied on the 45 steel balls and disks. Boundary lubrication tests are carried out on a self designed ball-on-disk machine, The base oil is pure 150SN oil, and oleic acid as additive are added into the lubricant. Disks have surface roughness values （Ra） of 0.8 μn and 0.4 μn. The electrical contact resistance method is used to determine the lubrication status. Hypothesize that the molecular film is monomolecular layer in condensed state and the opposing surfaces are completely separated by molecular film. A boundary lubrication model is established according to experimental results and hypothesizes. The experimental and calculatienal results show that the adsorption of polar molecules on steel surface is the main factor to form the boundary lubrication film. Load and sliding speed contribute little to the friction coefficient of boundary lubrication. The properties of steel surface and additive for the lubricant significantly influence on the characters of boundary lubrication. The smaller the surface roughness value is, the smaller the friction coefficient of the boundary lubrication is.

Diffusion behavior of helium in titanium and the effect of grain boundaries revealed by molecular dynamics simulation

The microstructures of titanium（Ti）, an attractive tritium（T） storage material, will affect the evolution process of the retained helium（He）. Understanding the diffusion behavior of He at the atomic scale is crucial for the mechanism of material degradation. The novel diffusion behavior of He has been reported by molecular dynamics（MD） simulation for the bulk hcp-Ti system and the system with grain boundary（GB）. It is observed that the diffusion of He in the bulk hcp-Ti is significantly anisotropic（the diffusion coefficient of the [0001] direction is higher than that of the basal plane）,as represented by the different migration energies. Different from convention, the GB accelerates the diffusion of He in one direction but not in the other. It is observed that a twin boundary（TB） can serve as an effective trapped region for He.The TB accelerates diffusion of He in the direction perpendicular to the twinning direction（TD）, while it decelerates the diffusion in the TD. This finding is attributable to the change of diffusion path caused by the distortion of the local favorable site for He and the change of its number in the TB region.

Effect of grain boundary structures on the behavior of He defects in Ni:An atomistic study

We investigated the effect of grain boundary structures on the trapping strength of HeN（N is the number of helium atoms） defects in the grain boundaries of nickel. The results suggest that the binding energy of an interstitial helium atom to the grain boundary plane is the strongest among all sites around the plane. The He_N defect is much more stable in nickel bulk than in the grain boundary plane. Besides, the binding energy of an interstitial helium atom to a vacancy is stronger than that to a grain boundary plane. The binding strength between the grain boundary and the HeN defect increases with the defect size. Moreover, the binding strength of the HeN defect to the Σ3（112）[110] grain boundary becomes much weaker than that to other grain boundaries as the defect size increases.