RESUMO
High entropy alloys (HEAs) of the type CrCuFeNiTi-Alx were processed through mechanical alloying. The aluminum concentration was varied in the alloy, to determine its effect on the HEAs' microstructure, phase formation, and chemical behavior. X-ray diffraction studies performed on the pressureless sintered samples revealed the presence of structures composed of face centered cubic (FCC) and body centered cubic (BCC) solid-solution phases. Since the valences of the elements that form the alloy are different, a nearly stoichiometric compound was obtained, increasing the final entropy of the alloy. The aluminum was partly responsible for this situation, which also favored transforming part of the FCC phase into BCC phase on the sintered bodies. X-ray diffraction also indicated the formation of different compounds with the alloy's metals. Bulk samples exhibited microstructures with different phases. The presence of these phases and the results of the chemical analyses revealed the formation of alloying elements that, in turn, formed a solid solution and, consequently, had a high entropy. From the corrosion tests, it could be concluded that the samples with a lower aluminum content were the most resistant to corrosion.
RESUMO
The aim of this study was to assess the accuracy of the copper/zinc ratio (Cu/Zn ratio) in the evaluation of a large group of patients with digestive cancer compared to gender and age-matched control subjects. A total of 282 patients was studied and separated into three groups: group I (n=75), patients with digestive cancer, group II (n=112), patients with bening digestive disease, and group II (n=95), healthy subject. Serum levels of copper and zinc were measured by atomic absorption spectrophotometry. The results showed that the serum levels of copper (mg/dL) in patients with digestive cancer (91.6 ñ27.3, p<0.05) were significantly higher than in patients with benign digestive diseasde (75.8 ñ 19.8) or healthy subjects (54.4 ñ 8.9) and the serum levels of zinc (mg/dl) were significantly lower (68.7 ñ 21.9, p<0.05) compared to benign digestive disease patients (80.1 ñ 18.7) or healthy subjects (100 ñ 11.4 mg/dl). The Cu/Zn ratio was also significantly higher in patients with digestive cancer (1.45 ñ .58, p<0.05) than those with benign digestive disease (0.95 ñ 0.28) or healthy subjects (0.55 ñ 0.13). Considering a cutoff value of 0.87, the sensitivity of the copper/zinc ratio was 82.2 percent, with a specificity of 65.7 percent, a positive predictive value of 45.8 percent and a negative predictive value of 91.3 percent. In conclusion, Cu/Zn ratio was found to be considerably higher in patients with digestive cancer compared to age-and gender-matched controls, with a sensitivity of 82.2 percent that might be useful in the evaluation of suspected malignancy