RESUMO
The nickel-based alloy Inconel 600, strengthened by solution treatment, finds extensive application as a heat exchange pipe material in steam generators within nuclear power plants, owing to its exceptional resistance to high-temperature corrosion. However, fretting corrosion occurs at the contact points between the pipe and support frame due to gas-liquid flow, leading to wear damage. This study investigates the fretting wear behavior and damage mechanism of the nickel-based alloy Inconel 600 and 304 stainless steel friction pairs under point contact conditions in a water environment. Characterization was performed using laser confocal scanning microscopy and scanning electron microscopy equipped with energy-dispersive spectroscopy. Results indicate that the friction coefficient remains consistent across different chloride ion concentrations, while the wear volume increases with increasing chloride concentrations. Notably, friction coefficient oscillations are observed in the gross slip regime (GSR). Moreover, the stability of the oxide layer formed in water is compromised, diminishing its protective effect against wear. In the partial slip regime (PSR), friction coefficient oscillations are absent. An oxide layer forms within the wear scar, with significantly fewer cracks compared to those within the oxide layer in the GSR. It is worth noting that in GSR, the friction coefficient oscillates.
RESUMO
This study aimed to investigate the clinical values of serum alpha-fetoprotein-L3 (AFP-L3) and Golgi protein 73 (GP73) in the diagnosis of hepatocellular carcinoma (HCC) with low alpha-fetoprotein (AFP). From January 2011 to December 2013, 50 low-AFP HCC patients confirmed by the color Doppler flow imaging (CDFI) and pathological examinations were collected. Forty-five patients with chronic liver diseases were also selected, including 29 liver cirrhosis patients, 15 chronic hepatitis B patients, and one severe hepatitis patient. Furthermore, 100 health volunteers with no evidence of benign or malignant liver diseases were included. The enzyme-linked immunosorbent assay (ELISA) method was applied to the GP73 quantitative assay. Serum AFP concentrations were determined using immunoassays utilizing enhanced chemiluminescence. Diagnostic accuracy of GP73 and AFP-L3 assays for low-AFP HCC was evaluated using receiver operating characteristic (ROC) curve analysis. Statistical analyses were conducted with the GraphPad Prism 5.0 software. Low-AFP HCC patients (35/50) exhibited higher positive rates of AFP-L3 than non-HCC patients (5/45) and healthy controls (2/100) (both P < 0.05). There were also significant differences in the positive rate of GP73 of low-AFP HCC patients (40/50) compared to those of non-HCC patients (3/45) and healthy controls (1/100) (both P < 0.05). However, no obvious differences in the positive rates of AFP-L3 and GP73 were observed between non-HCC patients and healthy controls (both P > 0.05). ROC curves showed that the area under the curve (AUC) of AFP-L3 for the diagnosis of low-AFP HCC was 0.6994 (sensitivity [Sen] = 70.0 %, specificity [Spe] = 95.2 %, accuracy = 88.7 %), while the AUC of GP73 was 0.8411 (Sen = 80.0 %, Spe = 97.2 %, accuracy = 92.8 %). Compared with single detection, the combination of AFP-L3 and GP73 levels for the diagnosis of low-AFP HCC showed higher Sen (94.0 %), Spe (93.1 %), and better accuracy (93.3 %). Our findings provide empirical evidence that the combination of AFP-L3 and GP73 is a good diagnostic strategy for low-AFP HCC.