Wear simulation of UHMWPE against the different counterface roughness in reciprocating unidirectional sliding motion.

Wear simulations of UHMWPE can economically and conveniently predict the performance of wear resistant bushings used for sealing or other reciprocating unidirectional sliding motion. In this study, pin on plate tribological experiments and microscopic analysis was done to obtained the wear profiles, wear volume and wear mechanism of UHMWPE against the counterface with different surface roughness of which Ra range is 0.03 ~ 2 µm. Meanwhile, the 3D wear simulation model of the pin on plate tribological experiments was established to discuss the adaptability of the energy and Archard wear model by analyzing the difference of wear profiles and wear volume between the experiment and simulation. The results indicate that with an increase in the counterface roughness, the wear simulation of UHMWPE estimated by the energy model were more accurate in reciprocating unidirectional sliding motion.

Value of the preoperative TNM staging and the longest tumor diameter measurement of gastric cancer evaluated by MSCT / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To explore the value of MSCT in the preoperative TNM staging and the longest tumor diameter measurement (RESIST standard) of gastric cancer.</p><p><b>METHODS</b>Clinical data of 153 consecutive patients with biopsy-confirmed gastric carcinoma who were preoperatively evaluated with enhanced MSCT scanning in our hospital from January 2012 to March 2013 were retrospectively analyzed. Consistency comparison was performed between preoperative TNM staging and the longest tumor diameter measurement and histopathological findings.</p><p><b>RESULTS</b>T-staging consistency of Kappa value was 0.566, and accuracy was 71.2%. N-staging consistency of Kappa value was 0.284, and accuracy was 47.7%. The Kappa value of M-staging consistency was 0.893, and accuracy was 98.7%. The overall accuracy of TNM staging consistency was 66.7% (102/153) with a Kappa value of 0.573. Effective measurement of the longest cancer diameter was carried out in 53 patients. There was no significant difference between preoperative longest tumor diameter acquired by MSCT and postoperative tumor measurement [(68.8 ± 40.6) mm vs. (64.2 ± 36.2) mm, P=0.969].</p><p><b>CONCLUSION</b>MSCT is accurate in preoperative TNM staging and longest tumor diameter measurement of gastric cancer compared with postoperative pathological examination, and can provide reliable evidence for preoperative staging and neoadjuvant therapy evaluation of gastric cancer, but it is unfavorable to evaluate the lymph node metastasis.</p>