ABSTRACT
Stresses reductions and/or raising the load-carrying capacity for a mechanical structure are always great dilemmas for researchers. In this article, a novel method is proposed, and its efficiency is examined for achieving these goals on functionally graded rotating nonuniform thickness discs. The originality of this method relies on comprising a geometrically well-defined area, into the whole structure, with certain homogeneous properties including density, thermal expansion coefficient, and elasticity matrix. This area acts as a reducer of the maximum values of various stress components. The solution of the magnetoelastic/magneto-thermoelastic problem is accomplished using the finite element method. The disc is subjected to partial uniform outer pressure, whereas, upon applying thermal loads; the thermal boundary conditions are considered symmetric. The proposed method is found to be beneficial as the obtained results demonstrated the ability to reduce the maximum stresses with different percentages depending on the location, angular width, and properties of the predefined area. This is reflected by an attainable decrease in the maximum compressive tangential stress and the von Mises stress by approximately 20.7% and 12.5%, respectively, under certain conditions.
ABSTRACT
OBJECTIVE: There is evidence of an increased incidence of insulin resistance and diabetes mellitus (DM) in patients with hepatitis C virus (HCV) infection. Several mechanisms have been proposed, including inadequate insulin secretion or interference with signaling within the insulin receptor. We assessed serum tumor necrosis factor alpha (TNFalpha) and ferritin levels as potential mediators of insulin resistance in HCV positive Egyptian patients. PATIENTS AND RESULTS: Patients (n = 27) with HCV infection, patients (n = 23) with hepatitis C and DM (HCV + DM), patients (n = 22) with DM, and sex- and age-matched controls (n = 18) were included in this study. The degree of insulin resistance (HOMA index) was significantly higher in the HCV, HCV + DM and DM groups compared to the controls. The mean +/- SD of the HOMA index was 4.53 +/- 2.84, 6.1 +/- 2.36, 3.69 +/- 2.2 and 1.32 +/- 0.49, in HCV, HCV + DM, DM and controls, respectively. Serum TNFalpha levels were significantly higher in the HCV, HCV + DM groups compared with the healthy controls and DM patients (p < 0.001). The median (range) values of TNFalpha in HCV, HCV + DM, DM patients and controls subjects were 25.5 (0.43-124.0), 19.8 (0.51-139), 0.85 (0-10.5) and 0.32 (0-5.8) pg/mL, respectively. There was a significant positive correlation between the HCV load and both HOMA index and TNF alpha level. HCV and HCV + DM patients also had significantly higher serum ferritin levels compared with healthy controls and patients with DM. The mean +/- SD of serum ferritin in HCV, HCV + DM, DM patients and controls subjects was 258.1 +/- 116.2, 285.8 +/- 124.3, 86.9 +/- 41.8 and 159.9 +/- 76.9 ng/mL, respectively. CONCLUSION: Patients with HCV infection had a significantly higher level of TNFalpha and ferritin which may explain their insulin resistance. HOMA index and serum TNFalpha levels correlated positively with the HCV load.
