Free convection of hybrid nanofluids in a C-shaped chamber under variable heat flux and magnetic field: simulation, sensitivity analysis, and artificial neural networks

In the present investigation, the free convection energFree convection of hybrid nanofluids in a C-shaped chamber under variable heat flux and magnetic field: simulation, sensitivity analysis, and artificial neural networksy transport was studied in a C-shaped tilted chamber with the inclination angle α that was filled with the MWCNT (MultiWall Carbon Nanotubes)-Fe3O4-H2O hybrid nanofluid and it is affected by the magnetic field and thermal flux. The control equations were numerically resolved by the finite element method (FEM). Then, using the artificial neural network (ANN) combined with the particles swarm optimization algorithm (PSO), the Nusselt number was predicted, followed by investigating the effect of parameters including the Rayleigh number (Ra), the Hartmann number (Ha), the nanoparticles concentration (ϕ), the inclination angle of the chamber (α), and the aspect ratio (AR) on the heat transfer rate. The results showed the high accuracy of the ANN optimized by the PSO algorithm in the prediction of the Nusselt number such that the mean squared error in the ANN model is 0.35, while in the ANN model, it was optimized using the PSO algorithm (ANN-PSO) is 0.22, suggesting the higher accuracy of the latter. It was also found that, among the studied parameters with an effect on the heat transfer rate, the Rayleigh number and aspect ratio have the greatest impact on the thermal transmission intensification. The obtained data also showed that a growth of the Hartmann number illustrates a reduction of the Nusselt number for high Rayleigh numbers and the heat transfer rate is almost constant for low Rayleigh number values

Evaluation of in-Hospital NT-ProBNP Changes in Heart Failure Patients to Identify the Six-Month Clinical Response Following Cardiac Resynchronization Therapy

N-terminal pro β-type natriuretic peptide (NT-proBNP) is a valuable marker for monitoring the response to treatment in patients with heart failure. Based on the clinically observed improvement of heart failure symptoms early after cardiac resynchronization therapy (CRT), we sought to investigate whether CRT induce any significant reduction in the plasma level of NT-proBNP in three days after implantation and whether it is correlated with patients' response at six months. In this prospective study, 21 consecutive patients with severe heart failure (New York Heart Association class 3.19±0.40) who underwent CRT were enrolled. Being alive, no hospitalization due to decompensated heart failure, and improvement of at least one NYHA functional class at six months were classified as clinical responsiveness. The plasma level of NT-proBNP was measured before, three days, and six months after CRT. Clinical evaluation, echocardiographic study, and six-minute walking test were performed before and six months after the procedure. At six months' follow-up, 16 (76.2%) patients were responders. The plasma level of NT-proBNP at three days after CRT increased almost equally in both responder and non-responder groups of patients (∆NT-proBNP was 40.94±135.74 vs. 54.80±88.98); however, at six months' follow-up, the NT-proBNP changes statistically differed across the two groups of patients (P=0.005). According to our findings, NT-proBNP percent deviation from baseline to three days after CRT appears to be not correlated with the patients' clinical response after six months, which was incongruent to the patients' clinical improvement after CRT