Improve the heat exchanger efficiency via examine the Graphene Oxide nanoparticles: a comprehensive study of the preparation and stability,predict the thermal conductivity and rheological properties,convection heat transfer and pressure drop

Journal of Thermal Analysis and Calorimetry - In this research, the effect of using GO/ water nanofluid as a coolant fluid in an isothermal heat transfer system was studied. At first, to evaluate...     

Simultaneous determination of levodopa, NADH, and tryptophan using carbon paste electrode modified with carbon nanotubes and ferrocenedicarboxylic acid

The redox response of a modified carbon nanotube paste electrode of ferrocenedicarboxylic acid was investigated. Cyclic voltammetry, differential pulse voltammetry, and chronoamperometry were used to investigate the electrochemical behavior of levodopa (LD) at modified electrode. Under the optimized conditions (pH 5.0), the modified electrode showed high electrocatalytic activity toward LD oxidation; the overpotential for the oxidation of LD was decreased by more than 190 mV, and the corresponding peak current increased significantly. Differential pulse voltammetric peak currents of LD increased linearly with its concentrations at the range of 0.04 to 1,100 μM, and the detection limit (3σ) was determined to be 12 nM. The diffusion coefficient ( D = 9.2 ×10 ^{- 6}cm²/s ) \left( {D = {9}.{2} \times {1}{0^{ - {6}}}{\hbox{c}}{{\hbox{m}}^2}/{\hbox{s}}} \right) and transfer coefficient (α = 0.49) of LD were also determined. Mixture of LD, NADH, and tryptophan (TRP) can be separated from one another by differential pulse voltammetry. These conditions are sufficient to allow determination of LD, NADH, and TRP both individually and simultaneously. The modified electrode showed good reproducibility, remarkable long-term stability, and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for determination of LD, NADH, and TRP in real samples such as urine and water samples.     

Highly Regioselective Ring Opening of Epoxides with Thiols Catalyzed by SbCl3 Under Solvent-Free Conditions

The ring-opening reaction of epoxides with thiols by SbCl ₃ supported on Kieselguhr under solvent-free conditions, afforded high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the less hindered side of the epoxides.     

MnSb2O6-chitosan nanocomposite: An efficient catalyst for the synthesis of coumarins via Pechmann reaction

In this work, MnSb₂O₆-chitosan nanocomposites were synthesized and have been employed in Pechmann condensation for the synthesis of coumarin derivatives. MnSb₂O₆-chitosan nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. The particles of MnSb₂O₆-chitosan have uniform spheres with sizes that are less than 100 nm. Simplicity, easy work-up, and short reaction times are advantages of this reaction. Also, we evaluated the antibacterial activity for some of the products, and the result showed significant pharmaceutical activities as antibacterial reagents against Staphylococcus aureus and Escherichia coli.     

Synthesis of bioactive magnetic nanoparticles spiro[indoline-3,4′-[1,3]dithiine]@Ni (NO3)2 supported on Fe3O4@SiO2@CPS as reusable nanocatalyst for the synthesis of functionalized 3,4-dihydro-2H-pyran

New bioactive magnetic nanoparticles of spiro[indoline-3,4′-[1,3]dithiine]@Ni (NO₃)₂ supported on Fe₃O₄@SiO₂@CPS were synthesized in five steps. The structure of synthesized magnetic nanoparticles was identified by using Energy-Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), Infrared spectroscopy (FT-IR), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Vibrating Sample Magnetometer (VSM) and Brunauer Emmett Teller (BET) surface analysis. Antimicrobial activity of the synthesized magnetic nanoparticles based on MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) and MFC (Minimum Fungicidal Concentration) values were also examined. Furthermore, the synthesized magnetic nanoparticles exhibited appropriate catalytic properties in the synthesis of the 3,4-dihydro-2H- pyran derivatives.