RESUMO
Cutting fluids are the most effective method to lower the cutting temperature and decrease the cutting tool wear. At the same time, the cutting fluids influence the corrosion resistance property of the machined surface. In this study, chlorinated paraffin (CP), which is a common additive in the cutting fluid, was selected as the research objective to study its corrosion resistance property. The passivation effect of CP with different concentrations on the machined surface of stainless steel was studied. Electrochemical measurements and surface morphology investigation were used to characterize the passivation effect of CP with different concentrations. The test results showed that the corrosion resistance of stainless steel in the cutting fluid was enhanced with the increase in CP additive. This reason is that the charge transfer resistance increases and the corrosion current density decreases with the increase in CP additive. The X-ray photoelectron spectroscopy (XPS) results show that the proportion of metal oxides on the processed surface of the stainless steel sample was increased from 20.4% to 22.0%, 32.9%, 26.6%, and 31.1% after adding 1 mL, 2 mL, 4 mL and 6 mL CP in the cutting fluid with a total volume of 500 mL, respectively. The oxidation reaction between CP and the stainless steel sample resulted in an increase in metal oxides proportion, which prevented the stainless steel sample from corrosion in cutting fluid.
RESUMO
BACKGROUND: In previous study, qRT-PCR analysis revealed significantly higher miR-182 levels in papillary thyroid carcinoma (PTC) than matched normal tissues. However, the clinical significance and prognostic value of miR-182 have not been investigated in PTC until now. METHODS: 151 pairs of PTC and adjacent normal thyroid tissues were obtained from Affiliated Hospital of Weifang Medical University from February 2008 to January 2015. The Chi square test was used to analyze the relationship between miR-182 expression and the clinicopathological characteristics. We used the Kaplan-Meier method and the log-rank test in univariate survival analysis, and we used the Cox proportional hazards regression model in our multivariate analysis. RESULTS: The relative expression of miR-182 in PTC samples was significantly higher than that of matched normal tissues (P<0.001). The high expression level of tissue miR-182 was statistically correlated with extrathyroidal invasion (P=0.009), cervical lymphnode metastasis (P=0.015), and TNM staging (P=0.001). The Kaplan-Meier method revealed that higher miR-182 expression level was correlated with significantly reduced overall survival. Furthermore, multivariate survival analysis revealed that miR-182 expression level (HR=2.882, 95% CI: 1.289-10.928, P=0.013) was significantly correlated with the poor prognosis of PTC patients. CONCLUSIONS: Overexpression of miR-182 is associated with aggressive clinicopathologic characteristics of PTC, and miR-182 might be a novel prognostic molecular marker of PTC.