Sharif University of TechnologyScientia Iranica1026-3098311220240601Electrodeposition of hierarchically structured superhydrophobic Ni-PTFE composite coating with remarkable corrosion resistance, chemical and mechanical stability9079192318010.24200/sci.2023.58385.5703ENM.Shamsaee ZafarghandiDepartment of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.N.Pirhady TavandashtiDepartment of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.Journal Article20210521One of the main problems of superhydrophobic coatings is the low mechanical and chemical stability, which limits the industrial applications of these coatings. The purpose of this research is to create Ni-PTFE composite coatings with hierarchical morphology by electrodeposition method, in order to increase the corrosion resistance, and to improve the mechanical and chemical stability. Ni-PTFE Composite coatings were fabricated by adding different concentrations of PTFE particles (5, 10, 15, 20, 30, and 40 g/L) into the Ni electrodeposition bath. The effect of PTFE concentration on morphology, wettability, and corrosion resistance of the coatings was investigated. The results showed that when an optimum concentration of PTFE (15 g/L) is introduced in the electrodeposition bath, not only the hierarchical morphology of the Ni coating is preserved; but also the maximum contact angle of 158° and the minimum corrosion current density of 0.03 µA/cm2 was achieved. The long-term chemical and mechanical stability tests showed that by embedding of PTFE particles with hydrophobic nature, into the hierarcically structured superhydrophobic nickel coatings, higher mechanical and chemical stability is obtaind.https://scientiairanica.sharif.edu/article_23180_cb4689f35aacb1b3b755fb7ba0a2d799.pdfSharif University of TechnologyScientia Iranica1026-3098311220240601Tuning the preferential direction of ion flow in asymmetric nanofluidic mediums9209342320110.24200/sci.2023.59514.6284ENM.BakirciFaculty of Aeronautics and Astronautics, Tarsus University, Mersin, 33400 TurkeyR.GarrenBatten College of Engineering and Technology, Old Dominion University, Norfolk, 23529 VA.Journal Article20211205Current rectification and electrokinetic flow properties in an asymmetric nanochannel in a thermoplastic polyurethane membrane were investigated experimentally and numerically. The nanochannel with a tip diameter of about 300 nm showed current rectification, which is evident only in nanochannels with much smaller tip radii (<100 nm), due to the surface properties of the thermoplastic polyurethane material. To elucidate the mechanism of current rectification, a mathematical model consisting of Nernst - Planck equations for the ionic mass transport, the Poisson’s equation for electrostatics, and Navier – Stokes equations for flow field has been developed. It was verified that the obtained numerical results were in qualitative agreement with the experimental results obtained. It was concluded that due to the surface charge of the channel material, a significantly thick electric double layer was formed on the inner surface of the nanochannel in contact with the electrolyte, and this formed a gating mechanism because of overlapping electric double layers near the tip of the asymmetric nanochannel. It has been found that the applied concentration gradient is as effective as low applied potentials and thus can reverse the preferential direction of ion flow.https://scientiairanica.sharif.edu/article_23201_0b6124f8a314cf73b1470cfa4ec1c474.pdfSharif University of TechnologyScientia Iranica1026-3098311220240601Entropy generation analysis for chemically reactive flow of Sutterby nanofluid considering radiation aspects9359442329610.24200/sci.2023.60105.6594ENW.Azeem Khan- Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80207, Jeddah 21589, Saudi Arabia.
- Department of Mathematics, Mohi-ud-Din Islamic University, Nerian Sharif, Azad Jammu and Kashmir 12010, Pakistan.N.AnjumDepartment of Mathematics, Mohi-ud-Din Islamic University, Nerian Sharif, Azad Jammu and Kashmir 12010, Pakistan.A.HobinyDepartment of Mathematics, Mohi-ud-Din Islamic University, Nerian Sharif, Azad Jammu and Kashmir 12010, Pakistan.M.AliDepartment of Mathematics, Mohi-ud-Din Islamic University, Nerian Sharif, Azad Jammu and Kashmir 12010, Pakistan.Journal Article20220310Nanofluids show greater heat transfer rate and characteristics of mechanical friction diminution using nano-sized hard elements to fluid. Moreover, regarding the working of heat transfer fluid, nanofluid is widely used in areas of refrigeration, shipping, automobile, chemical industry, energy, electronics, air conditioning, computer, and many other areas to cope heat transference issues. The aforesaid utilizations motivated us to encounter entropy generation aspects for Sutterby nanofluid flow configured by permeable surface. Moreover, well-known Buongiorno's model capturing same attributes of Brownian and thermophoretic-diffusions is presented for modeling and investigation. Additionally, (MHD) as well as thermal radiation effects are the part of current work. Here, we have also considered the viscous dissipation aspects. Similarity variable are used to decrease set of nonlinear PDEs into set of ODEs then resolved numerically by using bvp4c algorithm, besides the pertinent parameters are addressed graphically. The physical aspect of fluid flow, temperature, concentration for variation of involved parameters is explained with the help of graphs. Velocity of Sutterby nano fluid has opposite behaviors versus Sutterby fluid parameter and magnetic parameters. Augmented values of Brownian moment, thermophoresis and heat source parameters intensify the temperature of nanofluid. Concentration of Sutterby nanofluid deteriorates for greater Schmidt number.https://scientiairanica.sharif.edu/article_23296_fdef68fb05aa2a19850ee9d3b576de6c.pdfSharif University of TechnologyScientia Iranica1026-3098311220240601Numerical treatment for a nine-dimensional chaotic Lorenz model with the Rabotnov fractional-exponential kernel fractional derivative9459572318510.24200/sci.2023.61058.7123ENM.M.Khader- Department of Mathematics and Statistics, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh:
11566, Saudi Arabia.
- Department of Mathematics, Faculty of Science, Benha University, Benha, Egypt.Journal Article20220902In this paper, we will present an effective simulation to study the solution behavior of a high dimensional chaos by considering the nine-dimensional<br />Lorenz system through the Rabotnov fractional-exponential (RFE) kernel fractional derivative. First, we derive an approximate formula of the<br />fractional-order derivative of a polynomial function $t^{p}$ in terms of the RFE kernel. In this work, we use the spectral collocation method based<br />on the properties of the shifted Vieta-Lucas polynomials. This procedure converts the given model to a system of algebraic equations. We satisfy the<br />efficiency and the accuracy of the given procedure by evaluating the residual error function. The results obtained are compared with the results obtained<br />by using the fourth-order Runge-Kutta method. The results show that the implemented technique is easy and efficient tool to simulate the solution of such models.https://scientiairanica.sharif.edu/article_23185_de8b796905a821ca934ca788f3c9189b.pdfSharif University of TechnologyScientia Iranica1026-3098311220240601Investigation of structural, photo-luminescence and self-cleaning properties of thin layers of GO-ZnO and GO, GO-Ag and composite bilayer of GO-ZnO/GO-Ag prepared by spray pyrolysis method9589662341410.24200/sci.2023.61099.7140ENM. H.SaeedDepartment of Science, Mustansiriyah University, Collage of Basic Education, Baghdad, Iraq.S. M.AlduwaibDepartment of Science, Mustansiriyah University, Collage of Basic Education, Baghdad, Iraq.D. J. FakarAl-denDepartment of Science, Mustansiriyah University, Collage of Basic Education, Baghdad, Iraq.Journal Article20221024The synthesis of graphene oxide-zinc oxide, graphene oxide- silver, graphene oxide thin layers, and graphene oxide-zinc/graphene oxide-silver bilayer was done using a method called spray pyrolysis. Characterization of the synthesized layers was done by X ray diffraction, transmission electron microscope, atomic force microscope, photo-luminescence, FTIR and BET analyses. Based on the TEM images, the given nano-composites are formed and GO can be a suitable platform for the growth of silver and ZnO nano-particles and prevents their accumulation. According to the AFM images, GO-ZnO/GO-Ag sample has the lowest roughness. PL spectrum showed a broad emission peak for GO-Ag layer at a wavelength of approximately 550 nm, which is consistent with the reported band gap of 3.6eV. From BET results, the surface area was obtained 4 m2g-1 and 14 m2g-1, for GO and GO-Ag samples respectively which were greater than the similar work. The pore diameter of GO-ZnO sample was obtained equal to 16.5 nm, indicating the superiority of the meso-holes in GO-ZnO sample. Also, the surface area of GO-ZnO/GO-Ag bilayer was around 3.6 times larger than the surface area of ZnO. The contact angles of droplet with the surface in GO, GO-Ag, GO-ZnO, GO-ZnO/GO-Ag samples are 55.02, 60.24, 31.28, 56.35, respectively.https://scientiairanica.sharif.edu/article_23414_17f1f95b9ecaaa5774e65ddafd2d43ea.pdf